Multilayer composite pipe and pipe assemblies including reflective insulation

ABSTRACT

One aspect of the invention provides a composite refrigeration line set including: a suction line and a return line. One or more of the suction line and the return line are a composite refrigeration line set tube including: an inner plastic tube; a first adhesive layer circumferentially surrounding the inner plastic tube; an aluminum layer circumferentially surrounding the first adhesive layer and coupled to the inner plastic tube via the first adhesive layer; a second adhesive layer circumferentially surrounding the aluminum layer; and an outer plastic layer circumferentially surrounding the aluminum layer coupled to the aluminum layer via the second adhesive layer. The inner plastic tube is polyethylene of raised temperature. The outer plastic tube is polyethylene of raised temperature. The aluminum layer includes an alloy selected from the group consisting of: AL 3004-O, AL 3005-O, and AL 3555-O. The aluminum layer is butt-welded to itself.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation-in-part under 35 U.S.C. § 120 of U.S.patent application Ser. No. 16/931,571, filed Jul. 17, 2020, which is acontinuation under 35 U.S.C. § 120 of International Application No.PCT/US2020/024916, filed Mar. 26, 2020, which claims priority to U.S.Provisional Patent Application Ser. No. 62/824,235, filed Mar. 26, 2019;U.S. Provisional Patent Application Ser. No. 62/884,305, filed Aug. 8,2019; and U.S. Provisional Patent Application Ser. No. 62/957,491, filedJan. 6, 2020. The entire contents of these applications are herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

Multilayer composite pipes are designed and used to convey liquids,primarily water, for applications such as in floor heating, radiatorheating, and water supply.

SUMMARY OF THE INVENTION

One aspect of the invention provides a composite refrigeration line setincluding: a suction line and a return line. One or more of the suctionline and the return line are a composite refrigeration line set tubeincluding: an inner plastic tube; a first adhesive layercircumferentially surrounding the inner plastic tube; an aluminum layercircumferentially surrounding the first adhesive layer and coupled tothe inner plastic tube via the first adhesive layer; a second adhesivelayer circumferentially surrounding the aluminum layer; and an outerplastic layer circumferentially surrounding the aluminum layer coupledto the aluminum layer via the second adhesive layer. The inner plastictube is polyethylene of raised temperature. The outer plastic tube ispolyethylene of raised temperature. The aluminum layer includes an alloyselected from the group consisting of: AL 3004-O, AL 3005-O, and AL3555-O. The aluminum layer has a thickness within a corresponding rangefrom the following table:

Pipe Size (in) AL 3004-O (in) AL 3005-O (in) AL 3555-O (in)  ¼″ 0.01-0.014 0.014-0.02  0.01-0.016  ⅜″ 0.014-0.02 0.018-0.0260.016-0.022  ½″ 0.02-0.026 0.026-0.035 0.022-0.028  ⅝″ 0.024-0.0310.033-0.045 0.028-0.035  ¾″ 0.031-0.037 0.041-0.053 0.033-0.041  ⅞″0.035-0.043 0.045-0.061 0.037-0.047 1 ⅛″ 0.045-0.055 0.061-0.0770.049-0.059The aluminum layer is butt-welded to itself.

This aspect of the invention can have a variety of embodiments. Thealuminum layer may not include a corrosion-inhibiting protectivecoating.

The composite refrigeration line set can further include alow-emissivity layer circumferentially surrounding the outer plasticlayer. The low-emissivity layer can include low-emissivity aluminum. Thelow-emissivity layer can include a metallized film.

The composite refrigeration line set tube can have a burst pressure inexcess of 1950 pounds per square inch.

The composite refrigeration line set can further include a reinforcementlayer.

The composite refrigeration line set can further include: an outer pipesurrounding at least the suction line; and a plurality of spacerstructures. Each of the spacer structures can be positioned in intervalsalong the length of the suction line. Each spacer structure can maintaina gap between an outer surface of the suction line and an inner surfaceof the outer pipe. At least one of the outer surface of the suction lineand an inner surface of the outer pipe can include a low-emissivitylayer. The low-emissivity layer can include low-emissivity aluminum. Thelow-emissivity layer can include a metallized film. The return line canalso lie within the outer pipe.

Another aspect of the invention provides a refrigeration systemincluding: a compressor; an evaporator coil; the composite refrigerationline set as described herein coupled between the compressor and theevaporator coil to form a fluid circuit between the compressor and theevaporator coil; and a refrigerant received within the fluid circuit.

Another aspect of the invention provides a composite refrigeration lineset including: a suction line; and a return line. One or more of thesuction line and the return line are a composite refrigeration line settube including: an inner plastic tube; a first adhesive layercircumferentially surrounding the inner plastic tube; an aluminum layercircumferentially surrounding the first adhesive layer and coupled tothe inner plastic tube via the first adhesive layer; a second adhesivelayer circumferentially surrounding the aluminum layer; and an outerplastic layer circumferentially surrounding the aluminum layer coupledto the aluminum layer via the second adhesive layer. The inner plastictube is polyethylene of raised temperature. The outer plastic tube ispolyethylene of raised temperature. The aluminum layer includes AL3555-O. The aluminum layer has a thickness within a corresponding rangefrom the following table:

Pipe Size (in) AL 3555-O (in)  ¼″  0.01-0.016  ⅜″ 0.016-0.022  ½″0.022-0.028  ⅝″ 0.028-0.035  ¾″ 0.033-0.041  ⅞″ 0.037-0.047 1 ⅛″0.049-0.059

The aluminum layer is butt-welded to itself.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and desired objects of thepresent invention, reference is made to the following detaileddescription taken in conjunction with the accompanying drawing figureswherein like reference characters denote corresponding parts throughoutthe several views.

FIG. 1 depicts a plastic/gas-barrier/plastic composite tube according toan embodiment of the invention.

FIG. 2 depicts a composite tube including multiple metal layersaccording to an embodiment of the invention.

FIG. 3 depicts a schematic of a first embodiment of a pipe assembly withreflective insulation using a clip for spacing purposes according to anembodiment of the invention.

FIG. 4 depicts a cross section of the embodiment of FIG. 3 along theline II-II of FIG. 3.

FIG. 5 depicts a sectional view of another embodiment of the pipeassembly with a different spacer structure according to an embodiment ofthe invention.

FIG. 6 depicts a schematic of a third embodiment of the inventive pipeassembly with yet another spacer structure.

FIG. 7 depicts a cross section of an inventive pipe assembly withanother drawn-down spacer.

FIG. 8 depicts a line set pipe assembly in an unassembled stateaccording to an embodiment of the invention.

FIG. 9 depicts the line set pipe assembly of FIG. 8 in an assembledstate according to an embodiment of the invention.

FIG. 10 depicts the line set pipe assembly of FIG. 9 with a greaterlength to show the space surrounding the lines of the line set pipeassembly according to an embodiment of the invention.

FIG. 11 depicts a typical refrigeration system.

DEFINITIONS

The instant invention is most clearly understood with reference to thefollowing definitions:

As used herein, the singular form “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise.

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. “About” canbe understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%,0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear fromcontext, all numerical values provided herein are modified by the termabout.

As used herein, the term “alloy” refers to a homogenous mixture ormetallic solid solution composed of two or more elements. Examples ofalloys include austenitic nickel-chromium-based super-alloys (available,e.g., under the INCONEL® trademark from Huntington Alloys Corporation ofHuntington, W. Va.), brass, bronze, steel, low carbon steel, phosphorbronze, stainless steel, and the like.

As used in the specification and claims, the terms “comprises,”“comprising,” “containing,” “having,” and the like can have the meaningascribed to them in U.S. patent law and can mean “includes,”“including,” and the like.

As used in the specification and claims, the term “fiberglass” refers tofiber-reinforced plastic using glass fiber. Generally speaking,“E-glass” is understood to refer to alumina-calcium-borosilicate glassesused as a general purpose reinforcement where strength and highelectrical resistivity are desired, while “S-glass” is understood torefer to magnesium aluminosilicate glasses used for textile substratesor reinforcement in composite structural applications that require highstrength, modulus, and durability under conditions of extremetemperature or corrosive environments.

Unless specifically stated or obvious from context, the term “or,” asused herein, is understood to be inclusive.

As used herein, the term “metal” refers to any chemical element that isa good conductor of electricity and/or heat, and alloys thereof.Examples of metals include, but are not limited to, aluminum, cadmium,niobium (also known as “columbium”), copper, gold, iron, nickel,platinum, silver, tantalum, tin, titanium, zinc, zirconium, and thelike.

As used herein, the term “resin” refers to any synthetic or naturallyoccurring polymer. Ranges provided herein are understood to be shorthandfor all of the values within the range. For example, a range of 1 to 50is understood to include any number, combination of numbers, orsub-range from the group consisting 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,48, 49, or 50 (as well as fractions thereof unless the context clearlydictates otherwise).

DETAILED DESCRIPTION OF THE INVENTION

Multilayer Composite Pipes

Multilayer composite pipes can be fabricated from multiple layers ofmaterial including various plastics, adhesives and, in some cases metallayers. Exemplary constructions are summarized below.

TABLE 1 Exemplary Multilayer Composite Pipe Constructions Short NameComponents PE/AL/PE Polyethylene/Aluminum/Polyethylene PEX/AL/PEXCross-linked Polyethylene/Aluminum/ Cross-linked PolyethylenePERT/AL/PERT Polyethylene of raised temperature/Aluminum/ Polyethyleneof raised temperature

Referring to FIG. 1, these constructions can include an inner layer of atype of plastic 102, a layer of adhesive 104, a gas (e.g., oxygen)barrier (e.g., a layer of metal such as aluminum) 106, a layer ofadhesive 108, and an outer layer of a type of plastic 110.

Plastic layers 102, 110 can be selected from a variety of materials suchas thermoplastics, thermoplastic elastomers, polyethylene, polyethylene,polypropylene, polyvinyl chloride (PVC), polyamide, fluoropolymers,polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP),perfluroalkoxy alkane (PFA), and the like.

The metal layer(s) can be aluminum or aluminum alloys such asaluminum-manganese alloy. Exemplary aluminum alloys include the 1000series (e.g., 1050, 1070, and the like), 3000 series (e.g., 3003, 3004,3005, 3555, 3103, 3105, etc.), 5000 series (e.g., 5052) 6000 series(e.g., 6060, 6061, and the like), and 8000 series (e.g., 8006, 8011, andthe like). A variety of tempers can be utilized including -O (full soft(annealed).

In some embodiments, a corrosion-inhibiting protective coating can beapplied to alloys having high magnesium content (0.8% and greater suchas in AL 5052-O and AL 3004-O) to prevent blooming or oxidation of themagnesium on the surface of the aluminum alloy.

A variety of suitable thicknesses for alloys are provided below toachieve a burst pressure in excess of 1950 psi at ambient temperature.As can be seen, a multitude of thickness ranges for the reinforcementmaterial, pipe thickness, and reinforcement material composition can beused in the pipe construction, while still allowing for burst pressurethresholds to be in excess of the 1950 psi requirement for some pipinguse fields (e.g., Underwriters Laboratories Inc. Standard for Safety forRefrigerant Containing Components and Accessories, Nonelectrical (UL207)). (“Pipe size” is a nominal size to replicate the inner diameter ofACR soft copper tubing for the equivalent ACR soft copper outerdiameter. The relationship between the outer diameter and inner diameterfor ACR soft copper is provided as Table 3.)

TABLE 2 Thickness Ranges to Achieve 13.44 MPa Requirement Under UL 207Standard for Various Single-Aluminum-Alloy-Layer Composite Pipe PipeSize AL 5052-O Thickness AL 3004-O Thickness (in) (mm) (in) (mm) (in)(mm)  ¼″ 12  0.01-0.014 0.25-0.35  0.01-0.014 0.25-.035  ⅜″ 140.012-0.018  0.3-0.45 0.014-0.02 0.35-0.5  ½″ 16 0.018-0.024 0.45-0.6 0.02-0.026  0.5-0.65  ⅝″ 18 0.022-0.03 0.55-0.75 0.024-0.031  0.6-0.8 ¾″ 20 0.028-0.035  0.7-0.9 0.031-0.037  0.8-0.95  ⅞″ 25 0.031-0.039 0.8-1.0 0.035-0.043  0.9-1.1 1 ⅛″ 32 0.041-0.051 1.05-1.3 0.045-0.0551.15-1.4 Pipe Size ALERIS ® AL3555-O Thickness AL 3005-O Thickness (in)(mm) (in) (mm) (in) (mm)  ¼″ 12  0.01-0.016 0.25-0.4 0.014-0.02 0.35-0.5 ⅜″ 14 0.016-0.022  0.4-0.55  0.02-0.026  0.5-0.65  ½″ 16 0.022-0.0280.55-0.7 0.028-0.035  0.7-0.9  ⅝″ 18 0.028-0.035  0.7-0.9 0.035-0.045 0.9-1.15  ¾″ 20 0.033-0.041 0.85-1.05 0.043-0.053  1.1-1.35  ⅞″ 250.037-0.047 0.95-1.2 0.047-0.061  1.2-1.55 1 ⅛″ 32 0.049-0.059 1.25-1.50.063-0.077  1.6-1.95 Pipe Size AL 6061-O Thickness AL 3105-O Thickness(in) (mm) (in) (mm) (in) (mm)  ¼″ 12 0.014-0.022 0.35-0.55 0.016-0.022 0.4-0.55  ⅜″ 14  0.02-0.028  0.5-0.7 0.022-0.03 0.55-0.75  ½″ 16 0.03-0.037 0.75-0.95 0.031-0.041  0.8-1.05  5/8″ 18 0.037-0.0470.95-1.2 0.039-0.051  1.0-1.3  ¾″ 20 0.047-0.057  1.2-1.45 0.049-0.0591.25-1.5  ⅞″ 25 0.051-0.063  1.3-1.6 0.055-0.067  1.4-1.7 1 ⅛″ 320.067-0.081  1.7-2.05 0.071-0.087  1.8-2.2 Pipe Size AL 3003-O ThicknessAL 8006-O Thickness (in) (mm) (in) (mm) (in) (mm)  ¼″ 12 0.018-0.0240.45-0.6 0.018-0.024 0.45-0.6  ⅜″ 14 0.024-0.033  0.6-0.85 0.024-0.033 0.6-0.85  ½″ 16 0.033-0.043 0.85-1.1 0.033-0.043 0.85-1.1  ⅝″ 180.041-0.055 1.05-1.4 0.041-0.055 1.05-1.4  ¾″ 20 0.051-0.065  1.3-1.650.051-0.065  1.3-1.65  ⅞″ 25 0.059-0.073  1.5-1.85 0.059-0.073  1.5-1.851 ⅛″ 32 0.075-0.093  1.9-2.35 0.075-0.093  1.9-2.35

TABLE 3 Table 3 - ACR Copper Pipe Sizes (inches) Pipe Identification ¼″⅜″ ½″ ⅝″ ¾″ ⅞″ 1 ⅛″ Outer Diameter (OD) 0.25 0.375 0.5  0.625 0.75 0.8751.225 Inner Diameter (ID) 0.19 0.311 0.436 0.555 0.68 0.785 1.025Reinforcing Members

For common water conveyance applications, standard multilayer compositepipes are sufficient and work well given their flexibility andlight-weight nature. Also, given the previously mentioned benefits ofthe product, there are many other applications where this type of pipemay be used. These other applications could include the conveyance ofother types of liquids and gases such as refrigerants, natural gas,propane, and process and medical gases such as argon, helium, nitrogen,and the like. Depending on the application of the use for the multilayercomposite pipe, greater performance standards may be required making itnecessary to further enhance the standard multilayer product design toensure higher pressure and temperature limits. This enhancement can beaccomplished by adding yet another layer of material to the overallconstruction, thereby creating a reinforcement layer. Additionally oralternatively, the reinforcement can be added within the one of thelayers described above.

The reinforcement can be constructed in several forms. For example, thereinforcement can be spirally (e.g., helically) wrapped, longitudinal,braided, and the like under, over, or within any of the layers. Forexample, a reinforcement layer can be around or within the inner layerof plastic 102, around or within the outer layer of plastic 110, aroundthe gas (e.g., oxygen) barrier (e.g., metal) layer 106, or around orwithin the adhesive layers 104, 108. The reinforcement layer cancompletely cover or partially cover the surface of a pipe layer 102,104, 106, 108, 110.

The reinforcement material can include one or more individual materialspirals wrapped around the pipe (e.g., one material spirally wound withaxial pitch of 0.25″ or four spirals with individual pitch of 1″ or0.25″ collectively). Pipe capacity (e.g., in terms of burst strength)can be adjusted based on pitch, material selection, and the like. Forexample, the tubing can have a burst pressure in excess of 1,900 psi at70° F. and 1,500 psi at 200° F.

The reinforcement can include one or more materials such as metal foils(e.g., aluminum or copper), plastic films, metal wire, plastic wire,fiberglass cords or fabric (e.g., AR-glass, C-glass, D-glass, E-glass,E-CR-glass, R-glass, S-glass, and the like), any type of filamentmaterial, aramids, para-aramids, poly-aramid synthetic fibers, aromaticpolyester strands, and the like. The reinforcing materials can be coated(e.g., with a binder or primer), machined (e.g., roughened), etched, orotherwise treated to bond to or be embedded within the adhesive layers.In some embodiments, a particular adhesive layer (e.g., a tie resin, asolvent-based adhesive, a hot-melt adhesive, and the like) is utilizedto bond particular reinforcements.

In some embodiments, the reinforcement is applied after the product isextruded (e.g., a spiral wrap applied with a wrapping machine). In otherembodiments, a spiral wrap is formed with a rotating extrusion crossheadsuch that the spiral material is extruded within a layer of polymer oradhesive (e.g., wire inside polymer). In still another embodiment, aspiral wrap is formed with a rotating extrusion crosshead (e.g.,polyester cord extruded in a helix around an underlying tube). In stillanother embodiment, a longitudinal wrap can be added to any layer of thepipe.

Multiple Metal Foil Layers

Referring now to FIG. 2, another embodiment of the inventionincorporates multiple metal layers 206 a, 206 b.

Exemplary embodiments are described below from innermost layer tooutermost layer in descending order.

TABLE 4 Exemplary Multilayer Composite Pipe Constructions Embodiment AEmbodiment B Embodiment C Embodiment D Plastic 202 Plastic 202 Plastic202 Adhesive 204 Adhesive 204 Adhesive 204 Metal 206a Metal 206a Metal206a Metal 206a Adhesive 205 Adhesive 205 Adhesive 205 Metal 206b Metal206b Metal 206b Metal 206b Adhesive 208 Adhesive 208 Adhesive 208Plastic 210 Plastic 210 Plastic 210

Although embodiments having two metal layers 206 a, 206 b are describedabove, three or more metal layers could be utilized in accordance withthe invention.

The metal layers 206 a, 206 b can be the same or different with regardto one or more of material, thickness, or other properties. For example,either the inner metal layer 206 a or outer metal layer 206 b can bethicker than the other layer 206 b, 206 a. Each metal layer 206 a, 206 bcan be bonded to itself, e.g., through welding (e.g., overlap or butt)with methods such as ultrasonic, laser, tungsten inert gas, and thelike).

Adhesive 205 can have a sufficient compressive strength to preventelongation of metal layers 206 a, 206 b. Without being bound by theory,Applicant believes that most hot-melt adhesives would have sufficientcompressive strength properties.

Without being bound by theory, Applicant believes that a multilayercomposite pipe having multiple metal layers 206 a, 206 b havingthicknesses a and b, respectively, will have superior properties (e.g.,burst strength, bend radius, bending force, kink resistance) than amultilayer composite pipe having a single metal layer 106 of the samematerial of thickness c=a+b. For example, the metal layers 206 a, 206 bmay slide past each other during bends.

Multiple metal layers 206 a, 206 b also avoid single-point failures.Single-point failures in the metal layer can occur for a variety ofreasons, but some of the most common are poor weld integrity, reductionof strip thickness, and strip inclusions.

Current constructions of multilayer pipes utilize single aluminum layersthat are axially welded with methods such as ultrasonic, laser, andtungsten inert gas, etc. These welding methods can suffer from qualityissues that result in reduced strength of the aluminum layer at the weldor heat-affected zone. The locations of these affected areas are small,0.001″ (0.0254 mm) to 0.25″ (6.35 mm) in length and, in the case ofultrasonic welding, hidden from view, making conventional qualitymonitoring difficult. With a single layer of welded metal, the overallburst strength of the tubing can be significantly reduced because ofreduced weld quality. The addition of another layer of metal can providenecessary backing to prevent reduction in strength for single pointfailures. While the simplest construction places both weld seams in thesame radial location, further strength improvements are realized whenthe weld seams are located at opposite radial locations.

Similarly, single-layer metal can suffer decreased performance as aresult of reduced strip thickness. The metal strip used to fabricatemultilayer pipe can have the thickness inadvertently reduced severalways, with some occurring during the production of the strip and someduring the production of the multilayer pipe. Foreign-matter-inducedthinness is particularly difficult to identify and prevent. The strip isproduced by progressively rolling metal stock down to a suitablethickness. During this process, foreign matter that lands on the stockcan be rolled into the stock, creating a reduced thickness in arelatively small area. This can present as a single point failure in amultilayer pipe and can be prevented by the addition of a second layerof welded metal.

The metal strip can also have inclusions (foreign material) in the basematerial that are not homogenous or compatible with the alloy. After therolling process, these inclusions can cause a reduction in strength andmay present as a single point failure in a single layer of metal. Thiscan be prevented by the addition of a second layer of welded metal.

Pipe Assembly with Reflective Insulation

In another aspect of the invention, a pipe assembly can include an innercomponent, an outer component, and a reflective insulation systemarranged between the two components.

The inner component, hereinafter called the inner pipe, can be a pipe ofa diameter and structure/composition designed to transport a fluid therethrough, e.g., a refrigerant or other fluid needing insulation.

The outer component, hereinafter called the outer pipe, can also be apipe having a diameter larger than the inner pipe, the diameterdifference creating a gap that is part of a reflective insulation systembetween the inner pipe and the outer pipe that provides insulation valueto the pipe assembly.

One example of a reflective insulation system can be to include areflective material as part of the outer surface of the inner pipeand/or the inner surface of the outer pipe. In some embodiments, theouter pipe consists essentially or solely of a reflective material. Thisreflective material can be any kind of material having low emissivity(“low-e”) (e.g., having an emissivity value of 0.05 or less) to functionin the reflective insulation system and can be made part of the outersurface of the inner pipe in any way. For example, a film of low-ematerial can be adhered to the outer surface of the line set pipe usingan adhesive. The reflective layer can be roll-formed and welded orextruded over the inner most layer of the inner pipe. An example of suchan adhered material can be a layer of aluminum, which can be adhered tothe outer surface of the line set pipe using an adhesive, for example.For example, the low-e layer can be uncovered metal layer 206 b inEmbodiment C and provide both mechanical strength and low emissivity.The added outer layer of aluminum can provide a reflective low-e surfaceas part of the reflective insulation system. In some embodiments, theouter metal layer can be polished, either prior to or after formation ofthe inner pipe.

The other part of the reflective insulation system is a gap that iscreated by the diameter difference between the inner and outer pipe, thegap being of sufficient size to provide a meaningful R-value to the pipeassembly, e.g., at least that provided by foam insulation of the priorart. An example of such an R-value obtained by practicing the inventionis approximately an R-3.

Spacer structures can ensure that the gap between the inner pipe andouter pipe is maintained, so that the thermal effect of the reflectiveinsulation system along the length of the pipe assembly is notcompromised by a reduction in the gap size. The spacer structure tomaintain the gap can be achieved by a number of different techniques,including using components in addition to the inner and outer pipe orusing a part of the outer pipe as a spacer structure.

A first kind of spacer structure may be a mechanical kind, whereinspacers are positioned between the outer surface of the inner pipe andthe inner surface of the outer pipe. The spacers can also be spacedapart from each other and positioned along the length of the inner pipeso that the gap is maintained over the run or length of the pipeassembly. This embodiment is depicted in FIGS. 3 and 4, where a pipeassembly is designated by the reference numeral 30. The pipe assembly 30includes an inner pipe 31 having a reflective outer surface 33, e.g., analuminum layer. The inner pipe 31 can include a flow channel 32, whichallows fluid flow during use of the pipe assembly 30.

The outer pipe is designated by the reference numeral 35. The gapbetween the inner pipe and outer pipe is designated by the referencenumeral 37 and is created as a result of the diameter difference of theinner pipe 31 and outer pipe 35.

Also shown is a clip 39 as an exemplary spacer structure. In FIG. 4, theclip 49 is shown with a backwards c-shape, with its inner edge 46configured (e.g., complementary) to be adjacent to the outer aluminumsurface 43 of the inner pipe 41. An outer edge 44 of the clip 49 isconfigured to be adjacent to the inner surface 48 of the outer pipe. Theclip 49 can be secured between the inner pipe 41 and outer pipe 45 inany known way. Examples include a snap fit, where the clip 49 can besized to snap on the inner pipe 41. Another example can be a crimping,where the clip 49 can be deformed so as to grip the outer surface of theinner pipe 41, adhesives, and the like. The material of the clip 49 aswell as the inner pipe 41 and outer pipe 45 are discussed below. Havingthe clip 49 attach to the inner pipe 41 ensures that the clip 49 staysin place and the spacing between adjacent clips and the gap 47 are notdisrupted by one or more clips moving along the length of the inner pipe41. In essence, the low-e outer surface of the inner pipe 41, the gap47, the clips 49, and the outer pipe 45 together forms one embodiment ofa reflective insulation system for the pipe assembly that providesinsulating effect for the fluid flowing through the channel 42 of theinner pipe 41.

The spacing between adjacent clips along the run of the pipe assemblycan be such that the desired gap is maintained along the length of therun. Too large of a spacing between clips may cause the outer pipe tosag and narrow the gap, thereby affecting the thermal performance of thereflective insulation system. Small spacings are also unnecessary asthey can complicate the assembly process, increase cost by increasingthe number of spacers, etc. An exemplary spacing is believed to be about12 inches (about 30 cm) but other spacings, e.g., between 1 foot (about30 cm) spacing for bends and 6 foot spacing (about 180 cm) for straightruns, can be used as well.

While the gap 37 can be any practical dimension, it is preferred thatthe gap size range between ¼″ (0.636 cm) and 1½″ (about 3.8 cm), morepreferably range between ½″ (about 1.2 cm) and 1¾″ (3.175 cm), and mostpreferably be about 1 inch (2.54 cm). Too small of a gap can result in alow R-value for the reflective insulation system. Too large of a gap canincrease the overall diameter of the pipe assembly and can causeproblems in the installation as a result of this size increase. Toolarge of a gap can also increase the size of the outer pipe, whichincreases costs.

Instead of a clip or another mechanical device as a spacer structure, apart of the outer pipe can be employed as a spacer structure. Referringnow to FIG. 5, a second spacer structure embodiment is designated by thereference numeral 50. Here, the same inner pipe 58 with its aluminumouter surface 52 is employed. Instead of using the clips 49 as thespacer structure, the outer pipe, designated by the reference numeral51, is made with fins 53 extending from the outer pipe inner surface 57in radially-spaced apart locations. The FIG. 5 embodiment shows threefins 53 but more or fewer fins can be used to assist in maintaining thegap 57 along the length of the pipe assembly. Rather than theillustrated 120° spacings for the fins, four fins can be used, eachspaced apart 90° from an adjacent fin. In another example, two180°-spaced fins can be employed. The fins 53 can run the length of theouter pipe and can be sized in length so that a free end 55 of each fin53 is adjacent to the aluminum layer 52. In this embodiment, there is noneed for a connection between the free end 25 and the line set pipe 58,as the fins 53 together position the inner pipe 58 in an annularconfiguration with respect to the outer pipe 51. Preferably, the finsare an integral part of the outer pipe such that the fins can be madewhen the outer pipe is made. Then, the fin-containing outer pipe ispositioned around the inner pipe to form the pipe assembly. If the finsare made as separate components, the fins can be attached to either theinner pipe or outer pipe, e.g., some bonding technique using adhesives,welding, etc.

A third spacer structure can also involve components of the outer pipeitself. In this embodiment, the outer pipe includes drawn-down sectionsalong the length thereof. In this embodiment, and with reference toFIGS. 6 and 7, the pipe assembly is designated by the reference numeral60 and the outer pipe is designated by the reference numeral 61. Thesame inner pipe 61 and aluminum layer 66 of FIGS. 3-5 can be employed inthis embodiment.

FIG. 6 shows a side cross-sectional view of the pipe assembly showingthe outer pipe 61 with drawn down sections 63 positioned along a lengthof the outer pipe 61 and FIG. 7 shows a sectional view. The drawn-downsections can be formed in any manner, including as part of an extrudingprocess to make the outer pipe 71 or a later step once the outer pipe 71is made. For example, a crimping press can be used to create an annularor point drawn-down region.

The drawn-down section 73 functions as a spacer structure and is formedso that drawn down sections are spaced along the length of the outerpipe. The drawn down section 73 can maintain the gap 77 formed by thediameter difference between the inner pipe 74 and the outer pipe 71.While the spacing between adjacent drawn down sections 73 can vary, anexemplary range of a spacing is 1 to 6 feet, with a more preferredspacing of about 12 inches. The drawn-down sections can be made so thatthe inner surface 75 can contact the outer surface 76 of the inner pipe74.

While two drawn-down sections are illustrated, more than two drawn-downsections can be implemented, e.g., in spacings like that shown in FIG. 5for the fins 53 and described for this embodiment. The drawn-downsections may also be formed so as to have a 360° (i.e., annular)configuration and contact the inner pipe along its entire periphery.

The inner pipe can be composed of a variety of non-metallic, metallicmaterials, or combinations thereof, e.g., as described herein. Thenon-metallic materials preferably include one of thermoplastics andthermoplastic elastomers, and more preferably polyethylene, cross-linkedpolyethylene, polyethylene of raised temperature, polypropylene,polyvinyl chloride, polyamide, fluoropolymers, polyvinylidene fluoride,fluorinated ethylene propylene, perfluroalkoxy alkane, and the like. Thelow-e outer surface can occupy the outer surface of the inner pipe andcan be composed of roll-formed aluminum, extruded aluminum, or someother low-e surface-containing material, e.g., a metallized film that isreadily available on the market, that is part of the inner pipe 31. Thelow-e outer surface of the inner pipe can be a material separate fromthe inner pipe, e.g., a film that is bonded to the inner pipe oraluminum that is roll-formed and compressed to the inner pipe ordirectly extruding over the inner pipe. In this embodiment, the innerpipe 31 can constitute at least two layers, with the presence of thelow-e material of one layer creating the low-e outer surface of theinner pipe. The low-e outer surface functions as part of the reflectiveinsulation system with the gap formed between the plastic outer pipe andthe inner line set pipe, where the spacer structures can maintain thegap along the length of the pipe assembly.

The inner pipe 31 can also be composed of an aluminum pipe or othermetal pipe where the outer surface thereof functions as the low-esurface.

The outer pipe 35 can also be composed of any material that permits thecreation of the gap around the inner pipe. Examples include one ofthermoplastics and thermoplastic elastomers, and preferablypolyethylene, cross-linked polyethylene, polyethylene of raisedtemperature, polypropylene, polyvinyl chloride, polyamide,fluoropolymers, polyvinylidene fluoride, fluorinated ethylene propylene,perfluroalkoxy alkane, and the like. These polymeric materials canprovide a solid and durable plastic outer pipe. However, the plasticouter pipe can also be made of laminated plastic films, e.g., PET orsimilar materials, and can be sized to slide over the inner pipe,creating an air gap.

When using the clip 39 as a spacer, the clip can be composed of anymaterial, including metallic and non-metallic materials or combinationsthereof, that can provide sufficient support to create and maintain thegap of the reflective insulation system. Exemplary materials includemolded thermoplastics and thermoplastic elastomers, preferablypolyethylene, cross-linked polyethylene, polyethylene of raisedtemperature, polypropylene, polyvinyl chloride, polyamide,fluoropolymers, polyvinylidene fluoride, fluorinated ethylene propylene,perfluroalkoxy alkane, and the like. The clip 39 can also be composed ofa metallic material that can be stamped or cut to shape. The clip spacercan also be made of a foam material.

The same kind of materials described above for the FIG. 3 embodiment forthe inner pipe can also compose the inner pipe of the embodiments inFIGS. 5-7.

For the outer pipe of the embodiments of FIGS. 5-7, the outer pipe canalso have the type of construction described above for the outer pipedescribed for FIGS. 3 and 4.

While the reflective insulation system can include a low-e surface asthe outer surface of the inner pipe, the low-e surface can also belocated on the inner surface of the outer pipe 5. For example, the outerpipe 35 can include a low-e layer (e.g., aluminum or metallized film)bonded to the inner surface of the outer pipe 35. The techniques andtypes of material discussed above for providing the low-e surface aspart of the inner pipe 31 can also be employed for the inner surface ofthe outer pipe 35.

Yet another embodiment of the invention can include a reflectiveinsulation system with conventional line set piping. In this embodiment,both the suction or return line and the liquid line are employed alongwith a spacer and an outer thermal insulation sleeve. Referring to FIG.8, an unassembled pipe construction designated by the reference numeral80 is shown with a suction line 81 and liquid line 83, the two lines 81and 83 held in a spaced apart relationship by three spacers 85, and anouter thermal insulation sleeve 89. The spacers 85 are circular in shapeand define two openings, one opening designed to receive the liquid line83 and the other opening designed to receive the suction line 81. Thespacers 85 are separated from each other in a similar manner as thespacer structures and spacings using for the embodiments of FIGS. 3-7.The spacers can be made to attach to the lines 81 and 83 in the sameways as the clip 39 is attached to the inner pipe 31 so as to retain thespacers in a given location and maintain the space created by thediameter difference between the outer thermal insulation sleeve 89 andlines 81 and 83 along the length of the lines 81 and 83.

As shown in FIG. 9, the spacers, when measured in a cross sectionaldirection through the spacer and lines 92 and 93, create a gap orspacing 51 between the outer surfaces of two lines 92 and 93 and theperipheral edge 97 of the spacers and inner surface 98 of the outerthermal insulation sleeve 99.

For the construction of the lines 81 and 83, a variety of materials andconstructions can be used.

One multilayer pipe construction has an outer layer that is made of oneof thermoplastics and thermoplastic elastomers, preferably polyethylene,cross-linked polyethylene, polyethylene of raised temperature,polypropylene, polyvinyl chloride, polyamide, fluoropolymers,polyvinylidene fluoride, fluorinated ethylene propylene, perfluroalkoxyalkane, and the like. The outer layer is bonded to an aluminum orstainless steel layer that is bonded to an inner layer that is made ofone of thermoplastics and thermoplastic elastomers, preferablypolyethylene, cross-linked polyethylene, polyethylene of raisedtemperature, polypropylene, polyvinyl chloride, polyamide,fluoropolymers, polyvinylidene fluoride, fluorinated ethylene propylene,perfluroalkoxy alkane, and the like.

Another multilayer pipe construction has an outer aluminum or otherlow-e surface (low e optional) that is bonded to an inner layer that ismade of one of thermoplastics and thermoplastic elastomers, preferablypolyethylene, cross-linked polyethylene, polyethylene of raisedtemperature, polypropylene, polyvinyl chloride, polyamide,fluoropolymers, polyvinylidene fluoride, fluorinated ethylene propylene,perfluroalkoxy alkane, and the like.

Other possible materials and constructions for the lines 81 and 83include: solid aluminum pipe or some other solid metal with a low-esurface, although the low-e surface is optional on the lines 81 and 83,especially if the low-e surface is used as part of the outer sleeve 89;solid metal pipe (copper, stainless steel, etc.); and solid plastic pipethat is made of one of thermoplastics and thermoplastic elastomers,preferably polyethylene, cross-linked polyethylene, polyethylene ofraised temperature, polypropylene, polyvinyl chloride, polyamide,fluoropolymers, polyvinylidene fluoride, fluorinated ethylene propylene,perfluroalkoxy alkane, and the like.

As depicted in FIG. 10, the diameter of the sleeve 109 is made so thatit extends over the spacers and creates the space that surrounds thelines 101 and 103. With reference to FIG. 9, the line 92 is spaced fromthe inner surface of the sleeve 99, where the spacing distance isrepresented in one direction by line 93 in FIG. 9. The other line 95 isalso spaced a distance from the inner surface 98 of the outer thermalinsulation sleeve. While the distance between the line 92 and the sleeve99 is not uniform as a result of the presence of both lines 92 and 95 inthe space 91 (unlike the uniform gap in FIG. 3 for example), the space91 functions as a separation or gap between the outer surfaces of thelines 92 and 95 and the inner surface 98 of the outer thermal insulationsleeve 99. The space 91 cooperates in the formation of a reflectiveinsulation system for the pipe assembly 90. Once the lines 92 and 95 areassembled with the spacers 94, the outer thermal insulation sleeve 99can be slid over the spacers 94 to create the assembly 90. To create thereflective insulation system for the embodiment of FIGS. 8-10, the outerthermal insulation sleeve 99 is made, in one embodiment, with its innersurface being a low-e material, similar to the low-e surface of theinner pipe 31 of FIG. 3. An example of an outer thermal insulationsleeve can be a laminated plastic film with the reflective layer on theinside of the sleeve, with such a sleeve being flexible along its lengthand cross section. The outer thermal insulation sleeve can also be arigid pipe having a low-e material, e.g., aluminum, as part of theinside of the rigid pipe, e.g. a layer of aluminum or other low-ematerial bonded to the inside of the rigid pipe. The rigid pipe can alsobe a metallic material with a low-e surface, including an aluminum pipethat includes a highly reflective inner surface.

While the embodiments of FIGS. 8-10 use a low-e surface on the innersurface of the outer thermal insulation sleeve 99, one or both of thelines 92 and 95 can include low-e outer surfaces in substitution of thatfound on the inner surface of the sleeve 99.

While the outer thermal insulation sleeve 99 is shown with one type ofconstruction, e.g., plastic laminated film (PET or other similarmaterial) with an inner low-e surface, other constructions can beemployed. These constructions can include a multilayer pipe constructionwith an outer layer that is made of one of thermoplastics andthermoplastic elastomers, preferably polyethylene, cross-linkedpolyethylene, polyethylene of raised temperature, polypropylene,polyvinyl chloride, polyamide, fluoropolymers, polyvinylidene fluoride,fluorinated ethylene propylene, perfluroalkoxy alkane, and the likebonded to an inner aluminum or other low e surface. The outer thermalinsulation sleeve can also be solid aluminum pipe or some other solidmetal material having a low-e surface.

While the spacer 94 is shown as surrounding the lines 92 and 95, it canhave a different shape so long as the spacer sufficiently engages thelines 92 and 95 to hold them in a spaced apart relationship with eachother and the inner surface of the outer thermal insulation sleeve 99 soas to create the space for the reflective insulation system. The spacerconfiguration shown in FIGS. 8-10 can also include some attachmentfeature to the lines 92 and 95 or outer thermal insulation sleeve.However, such an attachment feature to hold the spacers in place can beoptional if the outer thermal insulation sleeve 99 is of a flexiblenature such that its engagement with the spacers can hold the spacers inplace. However, a clip like that shown in FIG. 3 can also be used, theclip having a cut out for each of the lines 92 and 95 and an attachmentfeature to secure the clip to the lines 92 and 95, e.g., crimping,snapping, and the like. The spacer 94 can be made out of the samematerials as outlined above for the clip 39.

A preferred construction of the pipe assembly of the embodiments ofFIGS. 3-10 can include an inner pipe that is made of one of apolyethylene of raised temperature (PERT) or a cross linked polyethylene(PEX) that includes an aluminum layer bonded to the outer surfacethereof, the aluminum layer functioning as the low-e surface of thereflective insulation system. The outer pipe can also be made of thesame polymeric materials as the inner pipe. Another preferredconstruction for the inner pipe is a pipe construction that includes twolayers of either PERT or PEX with an aluminum layer positioned inbetween these two layers. With this construction, if the inner pipe isto include the low-e surface, an additional layer can be added to theouter surface of the PERT-AL-PERT or PEX-AL-PEX pipe.

The inventive pipe construction has a number of advantages over theprior art pipe construction used for line sets and the like. Unlike thetypical line set construction that uses a foam insulation, the hardouter pipe better protects the pipe assembly from damage during theinstallation process. The hard outer pipe is also less likely to becompressed and a reduction in thermal properties is avoided, unlike theprior art line set wherein the foam insulation can be compressed and/ordamaged and thermal properties can be compromised. The outer pipe canstand up to the outside elements and will not deteriorate, which is notthe case for typical line set foam insulation.

Manufacturing advantages are also obtained with the inventive pipeconstruction as the outer pipe can be produced and installed over theinner pipe in the same production stream allowing for faster productiontimes. In contrast, when using the prior art foam insulation, the foamis separately manufactured and then later combined with a line set pipe,which is a much slower product making operation.

The foam insulation used in prior art pipes is normally extruded andthis kind of extrusion equipment is very costly compared to a simpleplastic pipe extrusion line. Also, the foam insulation extrusionequipment takes up greater floor space than that of a plastic pipeextrusion line and the extrusion process for making the foam insulationis very slow compared to that of a plastic pipe.

The inner and outer pipes, when cylindrical in shape, can be made in anyknown ways. When making the outer pipe having the fins or drawn downsections, the pipes can be extruded or the like. The spacers can bemolded if made from plastic or cut or stamped if made from metal.

When making the clip-using embodiment, generally, the clip can beattached to the inner pipe and then the outer pipe can be positionedover the spacer-containing inner pipe. The fin-containing outer pipe canbe extruded directly over the inner pipe. Similarly, the pipe having thedrawn-down sections can be extruded over the inner pipe and as part ofthe extruding process, the drawn-down sections can be formed. In thealternative, the outer pipe can be positioned over the inner pipe andthe drawn-down sections formed thereafter.

The inventive pipe assemblies can be used in any application thattypical line set piping is used. For example, the single pipe assemblyof FIGS. 3-7 can be used as the suction line in a line set providingrefrigeration for a given application such as that depicted in FIG. 11.The two line set of FIGS. 8-10 can be used in replacement of aconventional line set in a refrigeration system. However, this is onlyan example of a refrigeration system suitable to use the inventive pipeassemblies, and the pipe assemblies of the invention can be used inother systems.

In fact, any application where a pipe with a flowing fluid there throughor a set of pipes with flowing fluid are in need of insulation exists,the pipe assembly of the invention can be implemented, either where thepipe assembly uses a single pipe for fluid flow such as that disclosedin FIGS. 3-7, or an application that uses a plurality of lines or pipesas illustrated in FIGS. 8-10.

EQUIVALENTS

Although preferred embodiments of the invention have been describedusing specific terms, such description is for illustrative purposesonly, and it is to be understood that changes and variations may be madewithout departing from the spirit or scope of the following claims.

INCORPORATION BY REFERENCE

The entire contents of all patents, published patent applications, andother references cited herein are hereby expressly incorporated hereinin their entireties by reference.

The invention claimed is:
 1. A composite refrigeration line setcomprising: a suction line; and a return line; characterized in that oneor more of the suction line and the return line are a compositerefrigeration line set tube comprising: an inner plastic tube; a firstadhesive layer circumferentially surrounding the inner plastic tube; analuminum layer circumferentially surrounding the first adhesive layerand coupled to the inner plastic tube via the first adhesive layer; asecond adhesive layer circumferentially surrounding the aluminum layer;and an outer plastic layer circumferentially surrounding the aluminumlayer coupled to the aluminum layer via the second adhesive layer;wherein: the inner plastic tube is polyethylene of raised temperature;the outer plastic tube is polyethylene of raised temperature; thealuminum layer comprises an alloy selected from the group consisting of:AL 3004-O, AL 3005-O, and AL 3555-O; the aluminum layer has a thicknessrange for a given pipe size as follows for the indicated pipe sizes:Pipe Size (in) AL 3004-O (in) AL 3005-O (in) AL 3555-O (in)  ¼″ 0.01-0.014 0.014-0.02  0.01-0.016  ⅜″ 0.014-0.02 0.018-0.0260.016-0.022  ½″  0.02-0.026 0.026-0.035 0.022-0.028  ⅝″ 0.024-0.0310.033-0.045 0.028-0.035  ¾″ 0.031-0.037 0.041-0.053 0.033-0.041  ⅞″0.035-0.043 0.045-0.061 0.037-0.047 1 ⅛″ 0.045-0.055 0.061-0.0770.049-0.059

and; the aluminum layer is butt-welded to itself.
 2. The compositerefrigeration line set of claim 1, wherein the aluminum layer does notinclude a corrosion-inhibiting protective coating.
 3. The compositerefrigeration line set of claim 1, further comprising: a low-emissivitylayer circumferentially surrounding the outer plastic layer.
 4. Thecomposite refrigeration line set of claim 3, wherein the low-emissivitylayer comprises low-emissivity aluminum.
 5. The composite refrigerationline set of claim 3, wherein the low-emissivity layer comprises ametallized film.
 6. The composite refrigeration line set of claim 1,wherein the composite refrigeration line set tube has a burst pressurein excess of 1950 pounds per square inch.
 7. The composite refrigerationline set of claim 1, further comprising: a reinforcement layer.
 8. Thecomposite refrigeration line set of claim 1, further comprising: anouter pipe surrounding at least the suction line; and a plurality ofspacer structures, each of the spacer structures positioned in intervalsalong the length of the suction line, each spacer structure maintaininga gap between an outer surface of the suction line and an inner surfaceof the outer pipe.
 9. The composite refrigeration line set of claim 8,wherein at least one of the outer surface of the suction line and aninner surface of the outer pipe comprises a low-emissivity layer. 10.The composite refrigeration line set of claim 9, wherein thelow-emissivity layer comprises low-emissivity aluminum.
 11. Thecomposite refrigeration line set of claim 9, wherein the low-emissivitylayer comprises a metallized film.
 12. The composite refrigeration lineset of claim 9, wherein the return line also lies within the outer pipe.13. A refrigeration system comprising: a compressor; an evaporator coil;the composite refrigeration line set according to claim 1 coupledbetween the compressor and the evaporator coil to form a fluid circuitbetween the compressor and the evaporator coil; and a refrigerantreceived within the fluid circuit.
 14. A composite refrigeration lineset comprising: a suction line; and a return line; characterized in thatone or more of the suction line and the return line are a compositerefrigeration line set tube comprising: an inner plastic tube; a firstadhesive layer circumferentially surrounding the inner plastic tube; analuminum layer circumferentially surrounding the first adhesive layerand coupled to the inner plastic tube via the first adhesive layer; asecond adhesive layer circumferentially surrounding the aluminum layer;and an outer plastic layer circumferentially surrounding the aluminumlayer coupled to the aluminum layer via the second adhesive layer;wherein: the inner plastic tube is polyethylene of raised temperature;the outer plastic tube is polyethylene of raised temperature; thealuminum layer comprises AL 3555-O; the aluminum layer has a thicknessrange for a given pipe size as follows for the indicated pipe sizes:Pipe Size (in) AL 3555-O (in)  ¼″  0.01-0.016  ⅜″ 0.016-0.022  ½″0.022-0.028  ⅝″ 0.028-0.035  ¾″ 0.033-0.041  ⅞″ 0.037-0.047 1 ⅛″0.049-0.059

and; the aluminum layer is butt-welded to itself.